Segmental grinding wheel



Deg 1930- T. LARSSON 1 1,783,727

' SEGMENTAL GRINDING WHEEL Filed May '27, 1927 v III/1),.

Wi til 88888 gwpma to'c 7 Th are Larsso/z atbozweq Patented Dec.- 2,1936 UNITED STATES OFFICE F WORCESTER, MASSACHUSETTS, A CORPORATION 01MASSACHUSETTS SEGMENTAL GRINDING WHEEL Application filed m 27, 1927.serial No. 194,792.

This invention relates to grinding wheels and more particularly to agrindin wheel made up of segmentsof bonded abrasive held unitarily inposition for grinding.

It is found in modern grinding practice that it is not feasible torotate at a high speed a solid wheel made of abrasive grains bonded by avitrified ceramic material. Yet the efficiency of a large wheel rotatedrapidly is very high and there is increasing demand for wheels which areso constructed that they may be given a high surface speed ofrevolution. -It has been proposed hereto fore to form a grinding wheelof abrasive segments arranged in an annular shape and to hold themin'place by clamping devices, but such devices have not been whollysatisfactory, particularly as a design ca able of holding the segmentsproperly has een-cumbersome in ize and has projected beyond the sidefaces 0 the wheel so as to interfere with proper use of the wheel inlimited spaces.

The main objects of my invention are to provide a segmental grindingwheel in which gr a number of segments mounted in an annular form may beheld in position by clamping devices which do not interfere with thegrinding operation or full use of the ma chine, and in particular toprovide a segmental .wheel which is simple in design and may be easilymanufactured and quickly? assembled and which is so constructedandarranged'th'at the. abrasive segments may be made in the grindingwheel factory and shipped to the point of use and there mounted readiilyby unskilled laborers for use as desire It is a further object toprovide a segmental. grinding wheel which is so constructed and arrangedthat it may be rotated at a high rate of speed and used safely withoutdanger to the operator and which ma be of a larger diameter than hasbeen foun feasible, from the viewpoint of safety, for a monolithicvitrifled wheel.

One embodiment of my invention is shown in the drawings in which:

- F i re 1 is an end elevation of a segmental grin ing wheel completelyassembled and ready for use,

pose to form a grinding wheel of a number.

of abrasive segments so shaped and arranged that they may be positionedto form a grindmg annulus, and these segments may be held as a rigidwheel structure by means of clampmg plates or other suitable means. Thesegments are preferably cemented together to form a unitary rigid wheelstructure so that they may be shipped as a unit and then mounted betweenthe clamping plates on a inding machine at the'place of use. In order tohold the segments against the centrifugal force set up during grinding,they are each provided with shoulders on opposite sides thereof adaptedto be engaged by correspondingly shaped surfaces on suitable clampingmembers. These shoulders are preferably formed by recesses in the outersides of each segment which are separated by strengthening columns ofabrasive material. In order to keep the clamping plates within theplanes of the outer faces of the wheel the inner ends of the'segmentsmay be re-" duced in size, and the spaced recesses formed in the sidefaces of the reduced portion.

The clamping shoulders may be provided with shoes of metal or othersuitable material adapted to fit snugly against the clamping member andto transmit the clamping pressure over a wide area of the abrasive body.

As shown in the drawings, the segments 10 may be made of bonded abrasivematerial in the general shape and contour illustrated in Fig. 2, itbeing intended that in the form illustrated the partial cylindricalsurfaces 11' of the segments, when assembled,

face. 'ments are parallel or of suitable shape as is form a continuousperipheral grinding sur- The side faces 12 and 13 of the segdesired tomeet the requirements of a particular grinding operation. In order tohold the segments on the grinding wheel spindle, I provide clampingplates 15 and 16 which may be of suitable construction for mounting onthe spindle of a grinding machine. They are illustrated as consistingsimply of disk-shaped plates provided with central apertures 17 to fiton the spindle.

The segments are each provided with clamping shoulders so arranged thatsuitprovide a construction in which such clamping portions are left aslarge as is feasible. For this purpose, I provide the inherre ducedportion- 18 of each segment with spaced clamping grooves or recesses 19and 20 on opposite sides thereof which are separated by strengtheningcolumns of abrasive material. The lower portions of the recesses formshoulders arranged to contact with the corresponding parts on theclamping plates. The plates 15 and 16 have each an inwardly projectingflange cut away to form spaced lugs 21 and 22. These shoulders and lugsare preferably beveled and so shaped that when the plates are drawntogether by means of bolts 23 the wedge-shaped lugs 21 and 22 willinterfit with the recesses and seat against the shoulders on the lowerportions 0 the grooves 19 and 20 and so tend to draw the segmentsinwardly and into close relation to one another.

These shoulders are preferably provided with shoes and 31, and the uppersurfacesof the shoes are. so shaped that they will fit fairly wellagainst the wedge-shaped clamping surfaces of the lugs 21 and 22. Theseshoes are preferably made of some tough and durable material, such as aBabbitt metal, which may be cast in position and permeate the surfacepores of the segor other support provided for the pur ose, and theclamping forces there met wil be likewise distributed. It will beobserved upon inspection of the drawings that the clamping plates arecut away between their heads, and their lower thicker base portions sothat they will not contact with the sides of the segments, and theclamping forces fall entirely upon the metal shoes. As a simplemodification, I may form the shoe as two strips 37 and 38 (see Fig. 5)which are located in grooves in the inner peripheral corners of theassembled segments.

The segments are made in accordance with approved practice of abrasivegrains bonded by suitable material, such as a vitrified ceramic bond,and they are then provided with the various shoes as desired, afterwhich the segments are assembled in the correct position for use on thewheel. The segments are spaced apart slightly as will be observed oninspection of Fig. 1 and the crevices 40 between the end faces of thesesegments may be filled with a suitable cementitious material, such asBabbitt metal or a mixture of sulfur and ground-coke, which enters thesurface pores of the abrasive body and thereby'cements the segments intoa rigid unitary structure which may be shipped to the point of use andthere suitably mounted between the clamping plates. The plates 15 and 16are put in position, one on each side of the wheel and the cap screws 23are then utilized to draw them toward each other and interlock theparts. This serves to force the wed e-shaped lugs 21 and 22 against thebeve ed shoes on the segments and to clamp the abrasive segments tightlyin position and to secure them against the disruptive forces set upduring grinding. It will also be observed that the shoe 32 (Fig. 4) maybe made with a double bevel and the shoulders 34 and 35 correspondinglysloped so as to provide two further wedge surfaces which will aid inwedging the segments and plates tightly together. It will also beunderstood that the columns between the spaced recesses 19 and 20contain a considerable amount of abrasive material which strengthens thewheel, so that if the wheel is thin .there is still enough materialbetween the v clamping recesses to prevent breakage of the wheel duringgrinding.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A grinding wheel comprising segments of bonded abrasive grainsarranged in the form of an annulus which has a peripheral grinding face,side faces, and a reduced inner portion, and means including platesclamping against the reduced inner portion and locatedsubstantiallywithin parallel planes passing through said side faceswhich hold mean? I 3 the abrasive segments secured in position forgrinding. V

2. A grinding wheel comprising contiguous segments of bonded' abrasivegrains forming a peripheral grinding face and having inner reducedportions provided with clamping shoulders on their outer sides, shoesthereon, and clamping plates located within the planes of the side facesof the segments which have clamping members engaging said shoulders andsecure the segmentsin position.

3. A grinding wheel comprising abrasive segments arranged in the form ofan annulus having a reduced inner portion, each having.a slot inopposite side faces of said portion which is provided with a beveledclamping shoulder, clamping plates provided with beveled lugs "engagingsaid shoulders and means to hold the plates and segments thus assembled,said plates being located within parallel planes passing through thesides of the segments.

4. A grinding wheel comprisin abrasive segments arranged in the. form 0an annu lus having a peripheral grinding face and side faces, eachsegment having an inner reduced portion provided with a beveled clampingshoulder, two clamping members having beveled portions engaging saidshoulders and means to fasten the parts togethei, said clampingmembersbeing located wholly within parallel planes passing through theside faces of the abrasive segments.

5. A grinding wheel comprising segments arranged in the shape of anannulus, and having inner reduced portions, each of which has a slotforming a clamping shoulder on each outer side thereof, a shoe integralwith each shoulder, clamping members arranged one on each side of theannulus of the assembled segments which have lugs engaging theshoulders, and means to secure the parts together.

6. A grinding wheel comprising a plurality of abrasive segments mountedto form an annulus having a peripheral grinding surface and two sidefaces, each segment having an inner reduced portion provided withclamping shoulders, a: shoe integrally cast on each shoulder which has abeveled face, a clamping plate on each side of the annulus which lieswholly within a plane passing through the outer faces of the segmentsand has a beveled lug engaging said shoe, and means to fasten the platestogether.

7. A grinding wheel comprising a plurality of abrasive segments mountedto form an annulus having a peripheral grinding face and side faces,each segment having a reduced inner portion provided with a clampingshoulder on its opposite outer sides, a shoe on each shoulder and on theinner peripheral face of thesegment, a clamping plate on each side ofsaid annulus provided with a lug engaging and fitting against said shoeand a surface fitting against the inner shoe, and means to secure theplate together.

8. A grinding wheel comprising a series of abrasive segments cementedtogether to form a unitary annulus of abrasive material provided with aperipheral grinding face and sides, each abrasive segment havingareduced portion provided on its opposite outer sides with a slot havinga clamping shoulder, a shoe of metal on each clamping shoulder, andmeans including clamping plates on opposite sides of the annulushavingsurfaces' fitting against said shoes which are arranged to securethe segments rigidly in place.

9. A grinding wheel comprising segments of bonded abrasive grains unitedby a cementitious material into a rigid unitaryannulus which isindependent of a rotatable support, said annulus having side vfaces anda reduced inner portion, and means on the outer sides of said portionforming clamping shoulders which lie within parallel planes passingthrough the side faces.

10. A grinding wheel comprising abrasive segments united by a'cementitious material into a rigid unitary annulus having a reduced 12.A grinding wheel comprising abrasive I segments shaped and arran ed toform an annulus having a periphera grinding surface and an inner reducedportion, the outer sides of thelatter being provided with spaced slots,shoes therein forming shoulders adapt ed to be engaged by clampingmembers for mounting the wheel on a spindle, and a filler between thesegments which unites them into a unitary wheel structure.

13. A rinding wheel comprising a series of abrasive segments cementedtogether to form a unitary annulus of abrasive material provided with aperipheral grinding face and sides, each abrasive segment having aninner reduced portion provided with slots in opposite faces, metal shoescast in the slots and forming beveled clamping surfaces and shoes on theinner peripheral portions of phe segments for seating on a supportingsurace. 4 s

14. A grinding wheel comprising abrasive segments held together in theform of an annulus which has a peripheral grinding face and exposedsides, each segment havin recesses in its opposite exposed sides whicare separated by a strengthening column of abrasive, and shoes on thefaces of the recesses which are arranged to be engaged by clampingmembers to hold the abrasive annulus ona wheel spindle.

15. An abrasive segment comprising a body of bonded abrasive grainshaving a partial cylindrical grinding surface which is shaped to bemounted with similar bodies to form an annulus, a side face thereofbeing provided with recesses separated by a strengthening column, andsaid recesses having surfaces forming portions of a frustum of a, conewhich are adapted for engagement with clamping members arranged to holdthe segments mounted on a spindle.

16. An abrasive segment comprising a body of bonded abrasive grainshaving a partial cylindrical grinding surface, converging faces and sidefaces which is shaped to be mounted with similar bodies to form anannulus having its side faces exposed, the segment having a reducedportion'opposite to the cylindrical surface which is provided withrecesses in its side faces separated by a strengthening column of bondedabrasive material, said recesses forming clamping shoulders adapted tocooperate with clamping members to hold the segment in position on awheel spindle.

17. An abrasive-segment comprising a body of bonded abrasive grainshaving a partial cylindrical grinding surface, converging faces and sidefaces which is shaped to be mounted with similar bodies to form anannulus with its side faces exposed, the segment having a reducedportion opposite to the cylindrical surface which is provided withrecesses inits exposed side faces separated by a strengthening column ofbonded abrasive material and a metal shoe in each of said recesses whichprovides a clamping shoulder adapted to be engaged by a clamping memberto hold the segment in position on a wheel spindle.

18. A grinding wheel comprising a plurality of abrasive segmentsarranged as an annulus having a peripheral grinding surface and sidefaces and a reduced inner "portion providing recesses Within whichclamping plates may be located, said portion having spaced shouldersarranged to cooperate with lugs on the clamping plates, whereby theannulus may be supported thereon.

19. A grinding wheel comprising a plurality of abrasive segmentsarranged as an annulus having a peripheral grinding face and a reducedinner portion providing recesses in the sides of the wheel, and aclamping member in each recess having lugs thereon, said reduced oortionhavin clamping shoulders engaged by the lugs which are sep-

